6.6. SR 08-19-2002 - Laserfiche WebLink

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AET #20-02044 - Page 8 required, especially in some of the "cut" areas. If needed, the trench drains should discharge into the storm sewer system or storm water ponding areas. Excavation to install underground utilities may extend below the groundwater levels. We anticipate that use of a dewatering system may be required. The soils excavated during utility construction in the lower areas will likely be too wet to reuse in the trench backfill and place to specified compaction levels. Approach/Discussion Based on the soil boring data, it is our opinion that the deeper layers of very loose silty sand mixed alluvium at Borings//6 and #9 are potentially compressible and may densify under the weight of new fill needed to establish finish grades and the building foundation loadings. In our opinion, the potential for detrimental post construction settlement is greatest in areas where substantial thicknesses of fill are required. On the basis of the limited information available, we anticipate that removal of these soils can be avoided if the site development and grading plan and schedule can incorporate a building construction delay after placement of fill, and possible use of a temporary surcharging, dependent upon finish grades. We request we be allowed to review fmal development plans, when available, to judge whether this alternative remains feasible. If f'mal grades or project schedule do not allow this construction delay, deeper excavation will be needed. The recommendations presented in the following sections of this report are based on our assumption that the removal of the potentially compressible materials will not be required.